Objective: To compare the proportion of women with self-reported depression and anxiety symptoms at four months postpartum between mothers of singletons who conceived spontaneously and mothers who conceived with the aid of fertility treatment. Methods: The sample used for this study was drawn from The “All Our Babies Study”, a community-based prospective cohort of 1654 pregnant women who received prenatal care in Calgary, Alberta. This analysis included women utilizing fertility treatment and a randomly selected 1:2 comparison group. The data was collected via three questionnaires, two of which were mailed to the participants during pregnancy and one at four months postpartum. Symptoms of depression and anxiety at four months postpartum were measured using the Edinburg Postnatal Depression Scale and the Spielberger State Anxiety Inventory. Secondary outcomes of parenting morale and perceived stress were also evaluated. Descriptive statistics were used to characterize the population. Chi square tests and in cases of small cell sizes, Fisher Exact Tests were used to assess differences in postpartum mental health symptomatology between groups. Results: Seventy-six participants (5.9%) conceived using a form of fertility treatment. At four months postpartum, no significant differences were observed in the proportions reporting excessive depression symptoms (2.6% vs. 5.3%, p = 0.50), anxiety (8.1% vs. 16.9%, p = 0.08) or high perceived stress scores (7.9% vs. 13.3%, p = 0.23). Women who conceived with fertility treatment were less likely to score low on parenting morale compared to women who conceived spontaneously and this was particularly evident in primiparous women (12.5% vs. 33.8%, p = 0.01). There were no group differences in proportions reporting low parenting morale in multiparous women. Conclusion: This study suggests that at four months postpartum, the proportion of women who experience elevated symptoms of depression, anxiety or perceived stress do not differ between mothers who conceive using fertility treatment and those who conceive spontaneously. Parenting morale at four months postpartum is significantly lower in primiparous mothers conceiving spontaneously compared to those who conceive with fertility treatment.